Masses of non-observed "tails" of the asteroid families

prof. dr hab. Jacek Leliwa-Kopystyński, dr Ireneusz Włodarczyk

31 maja 2019 09:30, ul. Pasteura 5, sala B4.58

(Prezentacja po polsku) Selection of some Asteroid Families (AFs) from the data set containing more than 400000 numbered asteroids was the first step of this work. Hierarchical Clustering Method (HCM) of selection was applied. A full set of the N Asteroid Family Members (AFMs) of the considered family was ranged according to their masse (the density is assumed to be known). Next, the formula for asteroid mass distribution dn = Bm-γ dm was fitted in several intervals (n1, n2) where 1 < n1 < n2 < N’ < N. It was found, that the both parameters (B, γ) decreases when the interval (n1, n2) shifts to the larger numbers. This trend holds for all AFs considered. Basing of this we extrapolated mass distribution of each AF up to indefinitely small masses. This extrapolation allowed us to calculate the masses of the ‘tails’ composed of small asteroids. Of them most are non-observable. In consequence the masses of the whole AFs (including non-observed asteroids) are calculated. The latter are the lower limits of mass of the Parent Bodies (PBs) from which the families has been formed following an impact. Families considered in this work are 4 Vesta (0.0008), 221 Eos (0.7), 15 Eunomia (0.08), 20 Massalia (0.1), 24 Themis (0.6), 158 Koronis (0.95), and 3815 Konig (0.89). The figures in brackets denotes approximate values of the fraction f of primary mass MPB lost from the PB after an impact. Of these values considerable parts are the masses of the non-observed tails.